JP2925008B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a MOS field effect transistor (MOSFET) having raised sources and drains.
And a method for producing the same.

[0002]

2. Description of the Related Art In a miniaturized MOSFET, it is required to form a source / drain region at an extremely shallow junction in order to improve punch-through breakdown voltage. But,
If the junction is simply made shallow, the parasitic resistance of the source / drain increases, causing deterioration of device characteristics. In order to reduce the resistance of the source / drain region, an FET structure having a raised source and drain has been used. FIG. 3 is a cross-sectional view showing a conventional method of manufacturing a MOSFET having a raised source and drain disclosed in Japanese Patent Application Laid-Open No. 2-222153 in the order of steps.

As shown in FIG. 3A, a field oxide film 302 is formed in a device isolation region on the surface of a silicon substrate 301 by a selective oxidation method, and a gate oxide film 303 is formed in a device formation region on the surface of the silicon substrate 301. I do. Subsequently, a polycrystalline silicon film is deposited on the entire surface and patterned to form a gate electrode 304. Next, an insulating film made of an oxide film is deposited on the entire surface to a thickness of 200 ° to 900 °. This insulating film is etched back by anisotropic dry etching to form a thin sidewall spacer 305 made of this oxide film on the side surface of the gate electrode 304. Thereafter, an extremely shallow source / drain region 306 is formed by ion implantation. The source / drain region 306 is made of either an n-type material or a p-type material.
It is formed by implantation at a surface concentration of from × 10 ¹⁷ cm ^-3 to 1 × 10 ²⁰ cm ^-3 .

Next, as shown in FIG. 3B, a silicon film 307 is selectively formed on the upper surfaces of the gate electrode 304 and the source / drain regions 306 made of polycrystalline silicon by a chemical vapor deposition method. From 1000 to 200
Deposit by a thickness of 0 °. Next, as shown in FIG. 3 (c), an insulating film made of an oxide film is
This insulating film is etched back by anisotropic dry etching to form a side surface of the silicon film 307 formed on the first sidewall spacer and the upper surface of the gate electrode 304, and A second sidewall spacer 308 made of this oxide film is formed on the side surface of the silicon film 307 formed on the upper surface of the source / drain region 306. Next, as shown in FIG. 3D, a shallow source / drain region 309 is formed by ion implantation, and the silicon film 307 on the upper surface of the source / drain region 306 is doped with impurities to raise the raised source / drain region. A drain region 310 is formed.

Next, the raised source / drain regions 3
A titanium silicide layer 311 is formed on the upper surface of the gate electrode 10 and the upper surface of the gate electrode 304. This titanium silicide layer is formed by depositing a titanium layer on the entire surface and then reacting in a nitrogen atmosphere. At this time,
The raised source / drain region 310 and gate electrode 3
Only the silicon of 04 reacts with the titanium layer, and a titanium silicide layer 311 is formed. On the other hand, the titanium layer on the insulating film made of an oxide film reacts only with nitrogen in the atmosphere gas,
Converted to titanium nitride. Next, by selectively removing only this titanium nitride by wet etching,
The titanium silicide layer 311 can be selectively formed only on the upper surface of the raised source / drain region 310 and the upper surface of the gate electrode 304.

[0006]

However, according to the conventional manufacturing method shown in FIG. 3, between the gate electrode and the source / drain region or between the source / drain regions, the side wall spacer and the field oxide film are not covered. The problem of short-circuit occurs due to the silicon film partially deposited. That is, when a silicon film is selectively deposited on the upper surface of a gate electrode and the upper surfaces of source / drain regions by a chemical vapor deposition method (CVD method), an insulating film other than a portion where silicon is exposed may be deposited depending on CVD process conditions. Silicon also deposits on the upper part.

Further, even if a silicon film is deposited under the same process conditions, a silicon film may be deposited on a part of the insulating film depending on the surface condition of the silicon substrate before the silicon film is deposited. is there. Although the cause of the non-selective growth of the selective silicon is not clear, it is considered that the reason is that impurities on silicon nuclei that easily form nuclei are attached to a part of the insulating film. Therefore, a problem to be solved by the present invention is to make it possible to effectively prevent a short circuit caused by a silicon film formed on an insulating film by non-selective growth.

[0008]

As means for solving the above-mentioned problems, in the method of manufacturing a semiconductor device according to the present invention, a step of oxidizing a surface of a selectively grown silicon film after selective silicon growth and an oxide film thereof are provided. Etching step.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to the present invention comprises: (1) forming a gate electrode made of polycrystalline silicon on a first conductivity type semiconductor region via a gate insulating film; Due to the deposition of the insulating film and its etch back,
Forming a first sidewall spacer on a side surface of the gate electrode; (3) selectively growing a silicon film on the semiconductor substrate where silicon is exposed and on the gate electrode; (4) Oxidizing the surface of the selectively formed silicon film to form a thermal oxide film;
(5) a step of etching back the thermal oxide film to form a second sidewall spacer made of an oxide film on a side surface of the selectively formed silicon film; Doping the silicon film with a second conductivity type impurity during the selective growth of the silicon film in the step, or after the step (3), prior to the step (4), or in the step (5). After the step (d), a step of doping the silicon film with a second conductivity type impurity is added. Preferably, a refractory metal film is formed on the entire surface of the semiconductor device manufactured as described above, and a refractory metal silicide film is selectively formed on the upper surface of the selectively formed silicon film by heat treatment. Is added.

Another method of manufacturing a semiconductor device according to the present invention includes: (1) forming a gate electrode made of polycrystalline silicon on the first conductivity type semiconductor region via a gate insulating film; Forming a first sidewall spacer on the side surface of the gate electrode by depositing an insulating film and etching back the same; and (3) a second conductivity type using the gate electrode and the first sidewall spacer as a mask. Forming a source / drain region by doping an impurity; (4) selectively growing a silicon film on the source / drain region where silicon is exposed and on the gate electrode; (5) Forming a thermal oxide film by oxidizing the surface of the selectively formed silicon film;
(6) a step of etching back the thermal oxide film to form a second sidewall spacer made of an oxide film on a side surface of the selectively formed silicon film; and (7) a high melting point metal film on the entire surface. And selectively forming a refractory metal silicide film on the upper surface of the selectively formed silicon film by heat treatment. Preferably, all of the selectively formed silicon film is converted into a high melting point metal silicide film. Alternatively, in the step (4) of forming the silicon film, the silicon film is doped with the second conductivity type impurity or doped with the second conductivity type impurity except for a part of a portion to be silicided later. Do the growth.

More preferably, the (1)
After the step (i), prior to the step (2), a step of adding a second conductive type impurity at a low concentration in the surface region of the first conductive type semiconductor region using the gate electrode as a mask is added.

[Operation] As described above, when a silicon film is selectively deposited on the upper surface of the gate electrode and the upper surfaces of the source / drain regions, depending on the CVD process conditions or the surface condition of the silicon substrate, the silicon Although the silicon film is deposited on a part of the insulating film other than the exposed part, the present invention converts the silicon film deposited on a part of the insulating film into a silicon oxide film in a subsequent oxidation step. I do. Accordingly, it is possible to prevent a refractory metal silicide film from being formed on the insulating film, and to prevent a short circuit between the gate electrode and the source / drain region or between the source / drain regions. Further, the leak current between these regions can be reduced.

In general, even if silicon is deposited on an insulating film during selective growth of a silicon film, the amount of silicon deposited is much smaller on the insulating film than on silicon. This is because the nucleation density of silicon is lower on the insulating film than on silicon. Therefore, even if lightly oxidized, the silicon film on the insulating film can be completely oxidized. That is, even if the entire silicon film on the insulating film is oxidized, only a part of the surface of the selective silicon film on the silicon is oxidized, and the selective silicon film for forming the raised source / drain is almost unchanged. It is possible to leave.

In the present invention, an oxide film is also formed on the raised source / drain region or the side surface of the raised silicon film of the gate electrode. Therefore, in the step of forming titanium silicide, the raised source / drain region is formed. The problem that the gate electrode or the raised gate electrode and the raised source / drain region are short-circuited by the titanium silicide formed on the side surface can also be solved.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings. [First Embodiment] FIG. 1 is a sectional view showing a first embodiment of the present invention in the order of manufacturing steps. As shown in FIG. 1A, a field oxide film 1 having a thickness of 3000 ° is formed in a device isolation region on the surface of a p-type silicon substrate 101 by a selective oxidation method.
Then, a gate oxide film 103 having a thickness of 60 ° is formed in the element formation region on the surface of the p-type silicon substrate 101.
Subsequently, a polycrystalline silicon film having a thickness of 1500 ° is deposited and patterned on the entire surface to form a gate electrode 104. Next, an n-type impurity, for example, phosphorus (P) is accelerated at an energy of 20 to 30 keV and a dose of 1 × 10 ¹³ to 1 × 10 3.
Ion implantation is performed under the condition of ¹⁴ / cm ² to form an extremely shallow low concentration source / drain region 105. Next, an insulating film made of an oxide film is deposited on the entire surface to a thickness of 800 °, and this insulating film is etched back by anisotropic dry etching to form a first side made of the oxide film on the side surface of the gate electrode 104. A wall spacer 106 is formed.

Next, as shown in FIG. 1B, the upper surface of the gate electrode 104 made of polycrystalline silicon and the upper surface of the low concentration source / drain region 105 are formed by chemical vapor deposition (CVD). Selectively add 4 silicon films 107
Grow to a thickness of 00-800 °. Next, FIG.
As shown in (c), an oxide film having a thickness of 200 to 400 ° is formed on the surface of the selectively formed silicon film 107 by thermal oxidation. During the deposition of this silicon film,
On the field oxide film 102 or on the first sidewall
All of the thin silicon film deposited on a part of the spacer 106 is oxidized. Next, the thermal oxide film is etched back by anisotropic dry etching to form the gate electrode 10.
A thin second side wall spacer 108 made of this thermal oxide film is formed on the side surface of the silicon film 107 selectively formed on the upper surface of the substrate 4 and the upper surface of the low concentration source / drain region 105.

Next, as shown in FIG. 1D, an n-type impurity is implanted at an acceleration energy of 40 to 50 keV and a dose of 1
Ion implantation is performed under the condition of × 10 ¹⁵ to 1 × 10 ¹⁶ / cm ² to form a shallow high-concentration source / drain region 109 and to raise the silicon film formed on the upper surface of the low-concentration source / drain region 105. Source / drain regions 110. At this time, the gate electrode 104 and the silicon film raised on the gate electrode 104 are also doped at the same time, and the raised gate electrode 111 is formed. The impurity doping of the silicon film 107 is performed by adding, for example, phosphine (PH ₃ ) to the reaction gas at the time of depositing the silicon film instead of the ion implantation method, so that the impurity concentration is 1 × 10 ¹⁹ cm ⁻³ to 1 × 10 ^21. A doped silicon film of cm ⁻³ may be formed. In this case,
A part of the silicon film to be silicided later may not be doped with impurities. Next, a titanium silicide layer 112 is formed on the upper surface of the raised source / drain region 110 and the upper surface of the raised gate electrode 111. This titanium silicide layer is formed by depositing a titanium layer having a thickness of 300 ° on the entire surface and reacting the titanium layer with silicon in a nitrogen atmosphere. At this time, only the raised source / drain region 110 and the raised silicon of the gate electrode 111 react with the titanium layer to form a titanium silicide layer 112. On the other hand, the titanium layer on the insulating film made of an oxide film is converted into titanium nitride by reacting only with nitrogen in the atmospheric gas. Next, by selectively removing only the titanium nitride by wet etching, the raised source / drain regions 110 are removed.
The titanium silicide layer 112 can be selectively formed only on the upper surface of the gate electrode 111 and the raised upper surface of the gate electrode 111. In the above embodiment, the case where titanium was used was described. However, using a high melting point metal other than titanium, a high melting point metal was formed on the upper surfaces of the raised source / drain regions 110 and the raised gate electrode 111. Silicide may be formed.

[Second Embodiment] FIG. 2 is a sectional view showing a second embodiment of the present invention in the order of manufacturing steps. FIG. 2 (a)
As shown in FIG. 2, a 3000 .mu.m thick field oxide film 202 is formed in a device isolation region on the surface of a p-type silicon substrate 201 by a selective oxidation method, and a 60.degree. Gate oxide film 203
To form Subsequently, a polycrystalline silicon film having a thickness of 1500 ° is deposited on the entire surface and patterned to form a gate electrode 20.
4 is formed. Next, an n-type impurity such as phosphorus is accelerated at an acceleration energy of 20 to 30 keV and a dose of 1 × 10 ¹³ to 1 ×
10 ¹⁴ / cm ² conditions by ion implantation to form the source and drain regions 205 of the very shallow low concentrations. Next, an insulating film made of an oxide film is deposited on the entire surface to a thickness of 800 °, and the insulating film is etched back by anisotropic dry etching to form a first film made of the oxide film on the side surface of the gate electrode 204. Form sidewall spacers 206. Next, the n-type impurity is accelerated at an energy of 30 to 40 ke.
V, ion implantation under the conditions of a dose of 1 × 10 ¹⁵ to 1 × 10 ¹⁶ / cm ² to form a shallow high-concentration source / drain region 2
07 and doping of the gate electrode 204 is performed at the same time.

Next, as shown in FIG. 2B, the upper surface of the gate electrode 204 made of polycrystalline silicon and the high concentration source / drain regions 20 are formed by chemical vapor deposition.
7, a silicon film 208 is selectively grown to a thickness of 400 °. Next, as shown in FIG.
An oxide film having a thickness of 200 ° is formed on the surface of the selectively formed silicon film 208 by thermal oxidation. At this time, the field oxide film 202 is selectively grown during the selective growth of the silicon film 208.
All of the thin silicon film deposited on and on the first sidewall spacer 206 is partially oxidized. next,
The thermal oxide film is etched back by anisotropic dry etching, and the side surface of the silicon film 208 selectively formed on the upper surface of the gate electrode 204 and the upper surface of the high-concentration source / drain region 207 is covered with the thermal oxide film. A thin second sidewall spacer 209 is formed. At this time, the upper surface of the gate electrode 204 and the source
The thickness of the silicon film 208 selectively formed on the upper surface of the drain region 207 is set to 300 by thermal oxidation and etch back.
Å decrease to about.

Next, as shown in FIG. 2D, a silicon film 208 selectively formed on the upper surface of the gate electrode 204 and the upper surfaces of the high concentration source / drain regions 207.
And a part of the high concentration source / drain region and a part of the gate electrode are reacted with titanium to form a titanium silicide layer 2.
Convert to 10. In the second embodiment, unlike the first embodiment, the high-concentration source / drain regions 207 are formed before the silicon film 208 is formed. Is converted into titanium silicide, so that the silicon film 208 is not doped. In the second embodiment, the entirety of the selectively formed silicon film 208 is converted into a titanium silicide layer 208, thereby forming a titanium silicide layer 210.
And electrical conduction between the high-concentration source / drain 207 and
Electrical conduction between the titanium silicide layer 210 and the gate electrode 204 is obtained. Therefore, the selectively formed silicon film 2
08 is thinner than in the first embodiment. The titanium silicide layer 210 is formed by depositing a titanium layer having a thickness of 300 ° on the entire surface and reacting the titanium layer and silicon in a nitrogen atmosphere. At this time, only silicon reacts with the titanium layer, and a titanium silicide layer 210 having a thickness of 500 ° is formed. Since the formation of titanium silicide with a thickness of 500 ° consumes silicon having a thickness of about 500 °, the selectively formed silicon film 20 with a thickness of 300 ° before titanium silicide is formed.
8 and silicon at the surface of the high concentration source / drain 207 and silicon at the surface of the gate electrode 204.
00% will be consumed for the formation of titanium silicide. On the other hand, the titanium layer on the insulating film made of an oxide film is converted into titanium nitride by reacting only with nitrogen in the atmospheric gas.
Next, the titanium silicide layer 210 is selectively formed only on the upper surface of the high concentration source / drain region 207 and the upper surface of the gate electrode 204 by selectively removing only the titanium nitride by wet etching. Can be.

In the above embodiment, the case where titanium was used was described, but using a high melting point metal other than titanium,
Refractory metal silicide may be formed on the upper surface of the high concentration source / drain region 207 and the upper surface of the gate electrode 204. In the second embodiment, the silicon film 208 is formed as a non-doped silicon film. However, when the silicon film is deposited, an impurity doping gas is added to the reaction gas to deposit the silicon film. May be formed. Thus, a raised source / drain region can be formed below the titanium silicide layer. In this case, an impurity may not be doped into a part of the silicon film to be silicided later.

The following changes can be made to the first and second embodiments. For example, when the source / drain regions are formed close to the gate electrode due to outward diffusion of the high concentration source / drain regions, the formation of the low concentration source / drain regions 105 and 205 can be omitted. . If it is desired to increase the thickness of the second sidewall spacer, a thermal oxide film is formed on the surface of the selectively grown silicon film, and then the CV is formed.
After the D oxide film is formed, the etch back between the CVD oxide film and the thermal oxide film may be performed. First,
In the second embodiment, only the method of forming an n-channel MOSFET has been described.
Not only that, p-channel MOSFETs
It is also applicable to MOS.

[0023]

As described above, the method of manufacturing a semiconductor device according to the present invention comprises selectively growing a silicon film on a gate electrode and source / drain regions, and then performing an oxidation treatment and an etch back. Therefore, according to the present invention,
The problem of short-circuiting between the gate electrode and the source / drain region or between the source / drain regions due to the silicon film deposited on the sidewall spacers and a part of the field oxide film can be solved.
A MOSFET having a raised source and drain for obtaining an extremely shallow junction can be formed with high reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention in the order of steps.

FIG. 2 is a sectional view showing a second embodiment of the present invention in the order of steps.

FIG. 3 is a sectional view showing a conventional example in the order of steps.

[Explanation of symbols]

101, 201 p-type silicon substrate 102, 202, 302 field oxide film 103, 203, 303 gate oxide film 104, 204, 304 gate electrode 105, 205 low concentration source / drain region 106, 206, 305 first sidewall -Spacers 107, 208, 307 Silicon films 108, 209, 308 Second sidewall spacers 109, 207 High-concentration source / drain regions 110, 310 Raised source / drain regions 111 Raised gate electrodes 112, 210 311 titanium silicide layer 301 silicon substrate 306 source / drain region 309 source / drain region

Claims (7)

(57) [Claims] 1. A step of: (1) forming a gate electrode made of polycrystalline silicon on a first conductivity type semiconductor region via a gate insulating film; and (2) depositing an insulating film and etching back the same to form the gate. Forming a first sidewall spacer on the side surface of the electrode; (3) selectively growing a silicon film on the semiconductor substrate where silicon is exposed and on the gate electrode; Oxidizing the surface of the selectively formed silicon film to form a thermal oxide film; and (5) etching back the thermal oxide film to form an oxide film on a side surface of the selectively formed silicon film. Forming a second sidewall spacer; and doping the silicon film with a second conductivity type impurity during the selective growth of the silicon film in the step (3), or ) A step of adding a second conductivity type impurity to the silicon film before the step (4) after the step or after the step (5). Manufacturing method. 2. A refractory metal film is formed on the entire surface of the semiconductor device manufactured according to claim 1, and a refractory metal silicide film is selectively formed on an upper surface of the selectively formed silicon film by heat treatment. A method for manufacturing a semiconductor device, comprising the step of: 3. A step of (1 ') forming a gate electrode made of polycrystalline silicon on the first conductivity type semiconductor region via a gate insulating film; and (2') depositing an insulating film and etching back the same. Forming a first sidewall spacer on a side surface of the gate electrode; and (3 ′) doping a second conductivity type impurity with the gate electrode and the first sidewall spacer as a mask to form a source / drain region. (4 ') selectively growing a silicon film on the source / drain regions where the silicon is exposed and on the gate electrode; and (5') the selectively formed silicon Forming a thermal oxide film by oxidizing the surface of the film; and (6 ') etching back the thermal oxide film to form a thermal oxide film on a side surface of the selectively formed silicon film. (7 ') forming a refractory metal film over the entire surface and selectively forming a refractory metal silicide film on the upper surface of the selectively formed silicon film by heat treatment; A method for manufacturing a semiconductor device, comprising: 4. The method according to claim 3, wherein all of the selectively formed silicon film is converted into a refractory metal silicide film. 5. In the (4 ′) silicon film forming step, while doping a second conductivity type impurity, or
4. The method of manufacturing a semiconductor device according to claim 3, wherein the silicon film is grown while being doped with a second conductivity type impurity except for a part of a portion to be silicided later. 6. The method according to claim 1, wherein after the step (1), prior to the step (2), or after the step (1 ′), prior to the step (2 ′). Using a gate electrode as a mask, a second region is formed in the surface region of the first conductivity type semiconductor region.
4. The method for manufacturing a semiconductor device according to claim 1, further comprising a step of doping a conductive type impurity at a low concentration. 7. The method according to claim 1, further comprising: performing a chemical reaction after the step (4) prior to the step (5) or after the step (5 ′) and prior to the step (6 ′). An insulating film is deposited by a phase deposition method, and in the step (5) or the step (6 ′), the insulating film and the thermal oxide film are successively etched back to form a film on a side surface of the silicon film. 4. The method according to claim 1, wherein a sidewall spacer including an insulating film and the thermal oxide film is formed.